HLTB21H3 Lecture Notes - Francis Home, Antibiotics, Paramyxoviridae

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18 Apr 2012
Historical Perspective: 7th C historical confusion b/w smallpox, chicken pox, etc. Earliest description attributed to Persian dr
Rhazes (910 AD)- noticed pupil gets smaller when exposed to light clinically separated smallpox/measles - believed both
proceeded from same cause=false. Prevailing theory - red rash represented the mother's menstrual blood that accumulated during
pregnancy. Measles welcomed as way for child to rid himself of the so-called 'poison‘. Measles AKA rubeola, hard measles,
red measles, 9-day measles, morbilli (“little disease”), hasbah. Origins of ‘measles’ - ‘misellus’ or ‘misella’ = miserable
Modern History: 16/17th C 1670 - Thomas Sydenham's (Father of clinical observation) observed clinical features; via
description of his son's attack, clearly separate measles from smallpox, and recognized other complications, such as cancrum oris
(destruction of tissues around mouth/nasal cavity) and encephalitis (inflammation of brain, also caused by measles, herpes, etc).
Scientists rejected the mother's blood theory. 1757 - Francis Home demonstrated the infective nature - succeeded in transmitting
measles using blood from an infected child (in 8/10 child participants). Peter Ludwig Panum 1820 1885 -Sent by Danish
government to investigate an epidemic in Faeroe Isles in 1846 (b/w Norwegian sea/N. Atlantic ocean) following 65-yrs of being
disease-free. 1846- Approximately 7,800 inhabitants 102 died of measles. Panum conducted the first epidemiological study.
Faeroe Isles = ideal geographic location for an epidemiological study (cool temp, mountainous, coastal, house clusters .Arrival
of a boat noted in the local calendar. Visits from the Danish mainland were rare but visitors always recorded. Epidemic originated
fr. a single seaman from Copenhagen. On arrival, he had not recovered completely, was infectious. Panum followed the course of
the epidemic. (Context imp. b/c couse of infection was unintervened) He was able to establish 4 important facts:
1.Rash appears 12-14 days after contact with an infected person
2.Infectivity is greatest 3-4 days before rash appears
3.Contagious nature of disease via respiratory route of transmission (air droplets NOT of miasmatic origin-bad air)
4.Life-long immunity inhabitants over 64 yrs didn’t fall sick, childhood disease= lifelong immunity, didn’t fall sick at 2nd
Recent History: 20th C 1910 Hektoen (18631951) proved measles is present in blood. 1963 Enders (1897 1985)
(military turned scientist) isolated virus and produced vaccine. 1969 - Discovery of relationship between measles and a rare
degenerative disease - sub-acute sclerosing panencephalitis (brain inflammation), occurs 1 in 100,000, develops 5 to 10 years
after acute measles
Etiology: Family: Paramyxoviridae (contains RNA). Genus Morbillivirus. Infects respiratory system. Highly
communicable, transmitted by direct contact, fr nose/throat secretions of infected persons, primarily by droplet spread (clings to
air droplets, inhaled by ppl, so it cud be in/direct). Indirect contact via soiled articles, airborne transmission. Incubation period 7-
14 days. Period of communicability: 4d before until 4d after rash appears. Highly contagious (one of the most highly
communicable diseases). Virus can survive drying on micro-droplets in the air, but doesn’t live drying on on surfaces. Humans =
only hosts- so Human reservoir is a factor in whether an epidemic/spread will occur. Infants receive antibodies transplacentally
(can get passive immunity thru placenta). One exposure to infection = Lifelong immunity (Panum’s observ).
Clinical Manifestations:
3 Stages: after incubation, then fever, red rash, respiratory symptoms (3 c’s) (don’t need to know #days)
Prodrome (Prodomal) Stage (day 0): fever, 3 C`s: coryza (head cold), cough & conjunctivitis. Photophobia (increases in
severity). inflammation of the eye’s outer membrane (could be cause of photophobia)
Enanthem Stage (Late Prodrome): (2-4 d later) Koplik’s spots in mouth (sand-like whitish specks on reddened areas of
mucosal lining of mouth), Sore throat
Exanthem Stage (2-4d later): 1-2 d later, rash begins on face & neck trunk & extremities. Initially, colour is dark red, reaches
max. intensity in 3d, slowly fades to purplish color, then yellow-brown lesions with a fine scale over the following 5-10d
+ Late complications after lengthy SSPE (Sub-acute Sclerosing PanEncephalitis)
PERSON HAS TO BE INFECTED, not gender/age/race/status-specific, NO CARRIERS, with no vaccine coverage tends to be
endemic to children (specific to kids), school outbreaks, cycle of outbreaks every 2-5 yrs, severity can dep on nutrition, check 3
diagrams on blackboard
Diagnosis : type of rash, how it occurs, 3 c’s, antibody techniques, blood/serological tests, isolating virus (looking at it
Treatment: Supportive care, i.e. good hydration, good nutrition (limits intensity of disease). WHO recommends vitamin A given
w/ measles vaccination to offset deficiencies associated w/lack of vit A (blindness!) in the developing world. Antibiotics
sometimes given. most common practice: Quarantine
Epidemiology: Pre-vaccine period 130 M cases and 7-8 M measles-related deaths annually worldwide (child mortality rate,
7%). Virus still affects 50 M annually, causes more than 1 million deaths. Highest incidence in developing countries & naive
population (that hvnt been exposed). Naïve pop: 1848- 27% high case mortality rate in Hawaii, Fiji 20-25% died 1847, Samoa
Islands, all likely due lack of supportive care/treatment, bad nutrition/hydration, highly susceptible to an infection. Still occurs
infrequently in industrialized nations. Acute child fatality rate 0.1- 0.2% in industrialized nations VS 2-10% in developing world.
Amounts to 1.5 M deaths annually in developing countries. Cyclical every few yrs, but immunization in 20th C decreased death
rates tremendously. Spatial differences (WHO diagram): much higher in Africa vs. Americas. fr. 1990-95, all regions decreased.
Canada: cyclical patterns til vaccine approved e.g. BC in 1997 epidemic (unusually high for 20-29yrolds due to cyclic patterns,
naïvely exposed=most vulnerable vs. lower in kids due to vaccination in schools, better health care). US incidence decreased,
but % import/import-associated cases (infected travellers, just like Panum’s sailor) increased. Europe – high in UK, Switzerland,
Iceland- related w/notion that measles MMR vaccine leads to other diseases i.e. autism (refuted in April 2011)= yet still
movement against vaccine. Africa case study: 3 diff areas before/after vaccine implementation (Drastic difference) in Burkina
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